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Chemical reaction method for reducing free TDI (toluene diisocyanate) in non-toxic polyurethane curing agent

A chemical reaction and polyurethane technology, applied in the field of trimerization catalyst synthesis, can solve the problems of high free diisocyanate TDI content, low free TDI content, complex process, etc. Effect

Inactive Publication Date: 2013-07-03
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The present invention aims at the shortcomings of the polyurethane curing agent obtained by the existing preparation method, such as high free diisocyanate TDI content, large energy consumption and complex process by thin film evaporation, and provides a chemical reaction method with simple operation and no pollution to reduce the amount of non-toxic polyurethane curing agent. The method of free TDI synthesizes polyurethane curing agent prepolymer, with low content of free TDI and low viscosity, which meets the requirements of environmental protection and safe construction

Method used

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  • Chemical reaction method for reducing free TDI (toluene diisocyanate) in non-toxic polyurethane curing agent

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The preparation of Mannich base: in parts by weight, 188 parts of bisphenol A, 720 parts of 25% dimethylamine solution (the aqueous solution of dimethylamine, mass concentration) and 425 parts of 40% formaldehyde solution (formaldehyde aqueous solution, mass concentration) was heated at 80°C for 2 hours, after cooling, after the organic phase was separated, vacuum distillation was carried out at 90°C / 1.33Kpa to obtain the Mannich base to be prepared, and the reaction equation was as follows:

[0028]

[0029] In a four-neck flask equipped with a thermometer, an electromagnetic stirrer, and a reflux condenser, under the protection of nitrogen, add 153g of TDI-80 and 194.49g of butyl acetate, keep the water bath at 40°C, and stir for 10 minutes to make it evenly mixed. The mass ratio of 2,4-TD to 2,6-TDI in TDI-80 is 8:2. 26.19g of trimethylolpropane (TMP) was dehydrated with benzene, heated and melted, and kept in a liquid state using a heat preservation device. Then...

Embodiment 2

[0031] Preparation of Mannich base: The preparation method is the same as in Example 1, except that the phenol used is tert-butylphenol.

[0032] The NCO / OH molar ratio of toluene diisocyanate (TDI-80) and diethylene glycol is 3:1, and the water content of diethylene glycol is removed with xylene, and TDI-80 is added to the reaction kettle. The alcohol was added dropwise in half an hour, and under the protection of nitrogen, ethyl acetate was added as a solvent, and the reaction was carried out at 55° C. for 2 hours. Add 2,4-TDI whose mass is 10% of the initial isocyanate mass into the polyurethane prepolymer, and dropwise add the Mannich base catalyst prepared from p-tert-butylphenol, the amount of the catalyst is 0.1% of 2,4-TDI , 30 minutes to drop. The temperature was raised to 60° C. to continue the reaction for 4 hours, and phosphoric acid was added to terminate the reaction. Inhibitor phosphoric acid consumption is 1% of raw material gross weight. Cool down, stop and...

Embodiment 3

[0034] Preparation of Mannich base: The preparation method is the same as in Example 1, except that the phenol used is hexafluorobisphenol A.

[0035]The ratio of TDI-80 and glycerol is 4:1 according to the NCO / OH molar ratio, wherein the glycerol is dehydrated with cyclohexanone; add TDI-80 to the reaction kettle, and the glycerol is added dropwise in 40 minutes , under the protection of nitrogen, add toluene and xylene in a mass ratio of 1:1 and mix as a solvent, and react at 50° C. for 3 hours. Add 2,4-TDI whose mass is 20% of the initial isocyanate mass into the polyurethane prepolymer, then dropwise add hexafluorobisphenol A as the catalyst of the raw material, the amount of the catalyst is 0.05% of 2,4-TDI, drip for 40 minutes Finished adding. The temperature was raised to 75°C to continue the reaction for 4 hours, and acetyl chloride was added as a polymerization inhibitor. The amount of polymerization inhibitor acetyl chloride is 1% of the total weight of raw materia...

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Abstract

The invention discloses a chemical reaction method for reducing TDI (toluene diisocyanate) in a non-toxic polyurethane curing agent. A dehydrating agent is used to dehydrate a polyol, then the dehydrated polyol is added dropwise into the toluene diisocyanate TDI-80 and a solvent, the ratio of NCO to OH is between 3:1 and 4:1 according to molar ratio, the reaction is carried out at a lower temperature of 40 DEG C to 50 DEG C for 2 to 8 hours, 2,4-TDI with the mass of 10-20% of initial isocyanate is added to form a mixed system, a Mannich base trimer catalyst with the mass content of 2,4-TDI being 0.01-0.1% is added dropwise into the mixed system obtained in the second step, the temperature is raised to 50-75 DEG C to continue the reaction for 2-8 hours, and then a polymerization inhibitor is added dropwise to stop the reaction. The solid content of the obtained polyurethane curing agent is 50%, the NCO value is 7.05%-8.85%, the content of the free TDI is not higher than 0.4%, and the viscosity is between 700 mPa.s and 1400 mPa.s.

Description

technical field [0001] The invention relates to a technique for reducing free TDI of a polyurethane nontoxic curing agent by a chemical reaction method and a method for synthesizing a trimerization catalyst. Background technique [0002] Polyurethane coating has excellent performance, and since its birth, it has rapidly become the most important and most widely used coating variety. Widely used in various painting fields, polyurethane coatings are widely used as automotive coatings, wood coatings, building exterior wall coatings, metal anti-corrosion coatings, aerospace, aviation, ships, tanks and other coatings and invisible coatings. Among them, two-component polyurethane coatings account for the largest proportion in this variety of coatings and are most widely used. Two-component coatings consist of two components, one of which is a polyol component and the other is a curing agent containing isocyanate groups. However, the residual diisocyanate in the polyurethane curi...

Claims

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Application Information

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IPC IPC(8): C08G18/79C08G18/76C08G18/10B01J31/02C07C215/80C07C213/02
Inventor 黄洪陈卓司徒粤张心亚谢德龙
Owner SOUTH CHINA UNIV OF TECH
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